【摘要】 根据对云南、四川、甘肃三省九条主要河流干旱河谷的植物群落调查数据,对我国西南干旱河谷维管束植物区系的科、属分布区类型进行划分,并分析其地理分布格局。结果表明:(1)西南干旱河谷区的植物区系地理成分复杂,联系广泛,共包含11个科级和15个属级分布区类型;总体上,科、属两级热带/温带成分比例分别为3.06和1.77,显示了强烈的热带区系亲缘及温带区系的后期影响;与地中海–西亚至中亚植物区系存在一定联系;其东亚成分和中国特有成分比例低于亚热带区系平均水平,且中国–喜马拉雅成分比例高于中国–日本成分。(2)从西南向东北方向,植物区系的热带性质逐渐减弱,温带性质逐渐增强;科、属水平区系成分与古地中海–中亚区系的相似性逐渐增强;东亚和中国特有成分比例增加;南盘江与元江的干旱河谷植物区系之间存在中国–日本和中国–喜马拉雅成分的分界线。(3)根据干旱河谷植物属区系成分的比例构成将怒江、澜沧江和元江与其他流域分开,显示了长江溯源侵蚀和水系合并对西南诸河流植物区系发育的影响。更多还原

【Abstract】 Based on plant community data collected from dry valleys of nine major rivers in Gansu, Sichuan and Yunnan provinces of Southwest China, we divided the families and genera of the vascular plants into geographic elements of Chinese flora, and analyzed the spatial patterns. We found the flora of dry valleys of Southwest China revealed a complex composition of geographic elements with wide floristic connections, including 11 family area-types and 15 genera area-types. The ratio of tropical versus temperate floristic elements was 3.06 at the family level, and 1.77 at the genus level, showing a distinctive affinity for tropical floras, and later imprints of temperate floras. A clear floristic linkage existed between the dry valley floras and the Mediterranean, Western- and Central-Asian floras. The percentages of East Asian elements and endemic Chinese elements were below the average value in the flora found for the subtropical region in China. The Sino-Himalayan element had a value higher than that for the Sino-Japan element in the dry valley floras. The floristic affinity to the tropics weakened while affinity to temperate flora intensified moving in the region from the southwest to northeast. Linkages with the Mediterranean-Central Asian floras, and also the percentage of East Asian elements and endemic Chinese elements increased in the same direction. A boundary between the Sino-Japan type and Sino-Himalayan type was detected between the dry valley floras of Nanpanjiang River and Yuanjiang River. With respect to the genus level floristic composition of geographic elements, Nujiang River, Lancangjiang River and Yuanjiang River were separated from the other rivers, which are all upper branches of the Yangtze River. This departure indicated the impacts of the evolution of the Yangtze River, which were characterized by headward erosion, river confluences, on the characteristics of modern flora in dry valleys.更多还原